The present invention relates to a stacker-tyer capable of receiving a stream of sheet-like articles, forming the articles into a stack, and tying the stack.
Stackers for receiving signatures, newspapers, or other sheet-like articles in a stream and for forming them into stacks are well known. Typical are the stackers shown in U.S. Pat. Nos. 4,139,191; 4,037,525; 3,851,773; 3,538,818; 3,479,932; 3,450,275; 3,480,503; and 2,672,079. These stackers receive a stream of publications, form them into stacks and deposit them on a conveyor for subsequent handling. Known stackers can build stacks of a preselected count, and the count or number of publications selected may be adjustable. For example, stackers are known which are adjustable to form stacks of from 50 to 100 newspapers in each stack.
In some operations it is desirable to have the articles stacked in bundles up to about 12 inches high which are easily handled by an individual laborer. In other operations it is desirable to have the articles stacked to form logs up to 4 feet long which are easily handled by a forklift truck and which are suitable for feeding into automatic handling equipment. This would be the case in a newspaper printing plant where some sections of the newspaper are preprinted, e.g., the Sunday Magazine and advertising sections. These sections are thereafter collated with subsequently printed sections containing late news. The preprinted sections are stacked into logs which can be easily fed to an inserting or stuffing machine while the late news sections are fed directly from the press to a folder and then to the stuffing machine. On the other hand, a weekday paper may be printed all in a single press run, folded, and then stacked into bundles which can be easily handled by a delivery truck driver. To the applicants' knowledge, there is no single stacker which has the flexibility to form either bundles or logs.
Frequently, the stacks formed by a stacker are moved on a conveyor to a tying station where the stacks are tied prior to shipment. Commercially manufactured tyers are well known. One manufacturer of a tyer is the Signode Corporation, 2600 N. Western Avenue. Chicago, Ill. 60647. Tyers such as the ones made by Signode automatically feed a strap around a bundle, box, or other article, tighten the strap, cut the strap, and fasten the ends together.
One problem encountered in using a tyer in connection with a stacker which receives newspapers from a printing press concerns the speed of the tying operation relative to the speed of the press and stacker. A printing press at full speed can deliver over 70,000 newspapers per hour, and known stackers can handle this delivery rate. However, tyers can operate at only about one-half that speed, and as a result it is not uncommon to utilize two tyers with a single stacker.
Conveyor systems have been developed which alternately deliver stacks from the stacker to one or the other of two tyers. See, e.g., U.S. Pat. No. 4,037,525. However, these conveyor systems require a relatively large amount of floor space. Moreover, these conveyor systems have not proved entirely satisfactory because the conveyor itself may break down and because the stacks may become skewed or misaligned during movement on a conveyor from the stacker to the tyer especially where the conveyor is operating at a speed fast enough to keep up with a stacker connected directly with a high speed press.